TY  - JOUR
A1  - Inal, Sahika
A1  - Koelsch, Jonas D.
A1  - Chiappisi, Leonardo
A1  - Janietz, Dietmar
A1  - Gradzielski, Michael
A1  - Laschewsky, André
A1  - Neher, Dieter
T1  - Structure-related differences in the temperature-regulated fluorescence response of LCST type polymers
JF  - Journal of materials chemistry : C, Materials for optical and electronic devices
N2  - We demonstrate new fluorophore-labelled materials based on acrylamide and on oligo(ethylene glycol) (OEG) bearing thermoresponsive polymers for sensing purposes and investigate their thermally induced solubility transitions. It is found that the emission properties of the polarity-sensitive (solvatochromic) naphthalimide derivative attached to three different thermoresponsive polymers are highly specific to the exact chemical structure of the macromolecule. While the dye emits very weakly below the LCST when incorporated into poly(N-isopropylacrylamide) (pNIPAm) or into a polyacrylate backbone bearing only short OEG side chains, it is strongly emissive in polymethacrylates with longer OEG side chains. Heating of the aqueous solutions above their cloud point provokes an abrupt increase of the fluorescence intensity of the labelled pNIPAm, whereas the emission properties of the dye are rather unaffected as OEG-based polyacrylates and methacrylates undergo phase transition. Correlated with laser light scattering studies, these findings are ascribed to the different degrees of pre-aggregation of the chains at low temperatures and to the extent of dehydration that the phase transition evokes. It is concluded that although the temperature-triggered changes in the macroscopic absorption characteristics, related to large-scale alterations of the polymer chain conformation and aggregation, are well detectable and similar for these LCST-type polymers, the micro-environment provided to the dye within each polymer network differs substantially. Considering sensing applications, this finding is of great importance since the temperature-regulated fluorescence response of the polymer depends more on the macromolecular architecture than the type of reporter fluorophore.
Y1  - 2013
U6  - https://doi.org/10.1039/c3tc31304b
SN  - 2050-7526
VL  - 1
IS  - 40
SP  - 6603
EP  - 6612
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Inal, Sahika
A1  - Koelsch, Jonas D.
A1  - Chiappisi, Leonardo
A1  - Kraft, Mario
A1  - Gutacker, Andrea
A1  - Janietz, Dietmar
A1  - Scherf, Ullrich
A1  - Gradzielski, Michael
A1  - Laschewsky, André
A1  - Neher, Dieter
T1  - Temperature-Regulated Fluorescence Characteristics of Supramolecular
 Assemblies Formed By a Smart Polymer and a Conjugated Polyelectrolyte
JF  - MACROMOLECULAR CHEMISTRY AND PHYSICS
N2  - Aqueous mixtures of a coumarin-labeled non-ionic thermoresponsive copolymer and a cationic polythiophene exhibit marked changes in their fluorescence properties upon heating. At room temperature, emission from the label is significantly quenched due to energy transfer to the conjugated polyelectrolyte. Heating the mixture reduces the energy-transfer efficiency markedly, resulting in a clearly visible change of the emission color. Although the two macromolecules associate strongly at room temperature, the number of interacting sites is largely reduced upon the phase transition. Crucially, the intermolecular association does not suppress the responsiveness of the smart polymer, meaning that this concept should be applicable to chemo- or bioresponsive polymers with optical read-out, for example, as a sensor device.
KW  - aqueous solutions
KW  - conjugated polyelectrolytes
KW  - fluorescence (or Forster)
KW  - resonance energy transfer
KW  - phase transitions
KW  - thermoresponsive polymers
Y1  - 2013
U6  - https://doi.org/10.1002/macp.201200493
SN  - 1022-1352
VL  - 214
IS  - 4
SP  - 435
EP  - 445
PB  - WILEY-V C H VERLAG GMBH
CY  - WEINHEIM
ER  - 
TY  - JOUR
A1  - Inal, Sahika
A1  - Kölsch, Jonas D.
A1  - Chiappisi, Leonardo
A1  - Janietz, Dietmar
A1  - Gradzielski, Michael
A1  - Laschewsky, André
A1  - Neher, Dieter
T1  - Structure-related differences in the temperature-regulated fluorescence response of LCST type polymers
N2  - We demonstrate new fluorophore-labelled materials based on acrylamide and on oligo(ethylene glycol) (OEG) bearing thermoresponsive polymers for sensing purposes and investigate their thermally induced solubility transitions. It is found that the emission properties of the polarity-sensitive (solvatochromic) naphthalimide derivative attached to three different thermoresponsive polymers are highly specific to the exact chemical structure of the macromolecule. While the dye emits very weakly below the LCST when incorporated into poly(N-isopropylacrylamide) (pNIPAm) or into a polyacrylate backbone bearing only short OEG side chains, it is strongly emissive in polymethacrylates with longer OEG side chains. Heating of the aqueous solutions above their cloud point provokes an abrupt increase of the fluorescence intensity of the labelled pNIPAm, whereas the emission properties of the dye are rather unaffected as OEG-based polyacrylates and methacrylates undergo phase transition. Correlated with laser light scattering studies, these findings are ascribed to the different degrees of pre-aggregation of the chains at low temperatures and to the extent of dehydration that the phase transition evokes. It is concluded that although the temperature-triggered changes in the macroscopic absorption characteristics, related to large-scale alterations of the polymer chain conformation and aggregation, are well detectable and similar for these LCST-type polymers, the micro-environment provided to the dye within each polymer network differs substantially. Considering sensing applications, this finding is of great importance since the temperature-regulated fluorescence response of the polymer depends more on the macromolecular architecture than the type of reporter fluorophore.
Y1  - 2013
UR  - http://pubs.rsc.org/en/content/articlepdf/2013/tc/c3tc31304b
U6  - https://doi.org/10.1039/C3TC31304B
ER  - 
TY  - JOUR
A1  - Reiche, Jürgen
A1  - Dietel, Reinhard
A1  - Lemmetyinen, Helge
A1  - Janietz, Dietmar
A1  - Lemmetyinen, Helge
A1  - Brehmer, Ludwig
T1  - Edge-on Langmuir-Blodgett multilayers derived from disc-shaped multiyne mesogens
N2  - Langmuir-Blodgett(LB) multilayers were prepared from disc-shaped multiyne mesogens based on amphiphilic alkyl pentakis(aryl-ethynyl)benzene ethers. The two compounds used are characterized by five hydrophobic flexible chains and one hydrophilic substituent at the terminal position of the alkoxy chain. The LB films were analysed by X-ray scattering and spectroscopic measurements. An edge-on arrangement of the two discotic pentaalkynes within Y-type bilayers with a different packing density proved to be possible for the LB films of both compounds.
Y1  - 1992
ER  - 
TY  - JOUR
A1  - Reiche, Jürgen
A1  - Barberka, Thomas Andreas
A1  - Janietz, Dietmar
A1  - Hofmann, Dieter
A1  - Pietsch, Ullrich
A1  - Brehmer, Ludwig
T1  - X-ray structure investigation and computer modelling of Langmuir-Blodgett films formed from disc-shaped pentaalkines
Y1  - 1994
ER  - 
TY  - JOUR
A1  - Janietz, Dietmar
A1  - Festag, R.
A1  - Schmidt, C.
A1  - Wendorff, Joachim Heinz
T1  - Self-organization of new oligomers containing disc-shaped side groups
Y1  - 1994
ER  - 
TY  - JOUR
A1  - Janietz, Dietmar
A1  - Möbius, Dietmar
A1  - Festag, R.
A1  - Wendorff, Joachim Heinz
A1  - Ahuja, Rajeev C.
A1  - Reiche, Jürgen
T1  - Supramolecular organization of amphiphilic discotic mesogens
Y1  - 1994
ER  - 
TY  - JOUR
A1  - Angelova, Angelina
A1  - Reiche, Jürgen
A1  - Ionov, Radoslav
A1  - Janietz, Dietmar
A1  - Lemmetyinen, Helge
A1  - Brehmer, Ludwig
T1  - Control of the structure of Langmuir-Blodgett films of a discotic liquid crystalline compound via the subphase composition and the adjacent molecular environment
N2  - Changes of the molecular arrangenemt that can be induced by means of the LB technique in the multilayers of a disc-shaped multialkynyl amphiphile are monitored by means of small angle X-ray diffraction. Studies of the monolayers at the air-water interface reveal "edge-on" orientation of the discs. Specific effects of the counter- ions (Na+, Cd²+, Pb²+, and Ba²+) and sub-solution pH on the monolayer collapse pressure, transfer efficiency and molecular order in the multilayers are found. A correlation between the monolayer properties and the ability for formation of periodic discotic structures in the presence of divalent counterions is established. The discotic molecules retain their "edge-on" arrangement in the highly compressed transferred films with slight irregular interdigtation of the flexible wings and inclination to the substrate normal. The tilt and the inter- digitation are reduced when the discotic monolayers are deposited in alternating LB films with barium arachidate spacer layers.
Y1  - 1994
ER  - 
TY  - JOUR
A1  - Janietz, Dietmar
A1  - Hofmann, Dieter
A1  - Reiche, Jürgen
T1  - Molecular organization of amphiphilic disc-shaped penta-alkynes in LB-mono- and multilayers
N2  - Amphiphilic disc-shaped penta-alkynes were studied with regard to their molecular organization in Langmuir-Blod- gett (LB) mono- and multilayers. It was found that each compound investigated forms edge-on arranged stable monolayers at the air-water interface. LB-multilayers derived from fivefold pentyl-substituted pentaynes are characterized by an edge-on ordering of the molecules within Y-type bilayers. One of these compounds, containing a hydoxy substituent as hydrophilic head group, is exemplified and two possible rectangular molecular assemblies perpendicular to the substrate, each with a columnar in-plane packing, will be discussed as a result of molecular modelling. Based on the experimental results, hexagonal layer packing in the LB-film of a disc-shaped penta-alkynyl carboxylic acid without lateral substituents proved to be possible, which, furthermore, could be confirmed by molecular mechanics simulation.
Y1  - 1994
ER  - 
TY  - JOUR
A1  - Janietz, Dietmar
A1  - Ahuja, Rajeev C.
A1  - Möbius, Dietmar
T1  - Monomeric and oligomeric discotic amphiphiles at the air : water interface
Y1  - 1994
ER  - 
TY  - JOUR
A1  - Janietz, Dietmar
T1  - Neue discotische Amphiphile : Strukturbildung durch Formanisotropie und Funktionalisierung
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Frübing, Peter
A1  - Grasnick, G.
A1  - Herkner, G.
A1  - Janietz, Dietmar
A1  - Brehmer, Ludwig
T1  - Pyroelektrische Untersuchungen an Polyvinylalkoholen mit Azobenzen / Alkoxy - Seitenketten
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Jutila, Arimati
A1  - Janietz, Dietmar
A1  - Reiche, Jürgen
A1  - Lemmetyinen, Helge
T1  - Photophysical investigation of Langmuir-Blodgett films of amphiphilic discotic penta-alkynes
N2  - Amphiphilic discotic pentakis (arylethynyl) benzene compounds 1 and 2 containing an enlarged aromatic core functioning as a chromophoric p-electron system were studied with regard to their photophysical properties within Langmuir-Blodgett (LB) films. The results obtained from steady-state absorption as well as fluorescence excitation and emission measurements will be discussed with regard to interchromophoric interactions in the LB films. Time-resolved fluorescence inves6igations revealed the formation of a ground-state complex as well as excimer formation. Thermal treatment causes irreversible destruction of the LB film structure of the discotic amphiphiles. Within droplets the reorganization of the original nematic-discotic (ND) mesophase of the bulk materials was found for the alcohol 2 as indicated by a Maltese Cross texture, whereas the acid 1 remained isotopic.
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Marguet, S.
A1  - Markovitsi, D.
A1  - Germain, A.
A1  - Millie, P.
A1  - Daute, D.
A1  - Janietz, Dietmar
T1  - Experimental and theoretical study of the photophysical properties of multichromophoric molecules : the phenylethynylbenzene derivatives, light on organized molecular systems
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Janietz, Dietmar
A1  - Festag, R.
A1  - Schmidt, C.
A1  - Wendorff, Joachim Heinz
T1  - Supramolecular assemblies of new amphotropic oligomers with disc-shaped side groups
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Festag, R.
A1  - Schmidt, C.
A1  - Wendorff, Joachim Heinz
A1  - Janietz, Dietmar
T1  - Structure and dynamics of new triazine based polymers with discotic side groups
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Janietz, Dietmar
A1  - Festag, R.
A1  - Schmidt, C.
A1  - Tsukruk, V. V.
A1  - Wendorff, Joachim Heinz
T1  - Interfacial behaviour and thermal properties of triazine modified triphenylene oligomers
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Reiche, Jürgen
A1  - Janietz, Dietmar
A1  - Barberka, Thomas Andreas
A1  - Hofmann, Dieter
A1  - Brehmer, Ludwig
T1  - Comprehensive structure investigation of Langmuir-Blodgett films of disc-shaped molecules
N2  - The structure of mono- and multilayers of amphiphilic disc-shaped pentaynes wa inbestigated by Brewsterangle microscopy, X-ray specular reflection and grazing incidence diffraction (GID). X-ray specular reflection experiments confirm the "edge on" arrangement of the molecular discs. The molecular modelling of the Langmuir-Blodgett (LB)- multilayers predicts a columnar in-plane packing of the molecules. A GID experiment with monochromatic synchrotron radiation was used to verify the predicted multilayer structure on molecular level, while the Brewsterangle microscopy gave a deeper insight in the monolayer in-plane structure on micron scale.
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Janietz, Dietmar
A1  - Hofmann, Dieter
A1  - Reiche, Jürgen
T1  - Reply to comment on "Molecular organization of amphiphilic disc-shaped penta-alkynes in LB mono- and multilayers"
N2  - The model for the Langmuir-Blodgett (LB) film structure of amphiphilic disc-shaped penta-alkynes is refined. It is shown that LB experiments reported in a comment on one of our papers do not contradict the molecular organization within the LB films of the penta-alkynes we proposed.
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Tsukruk, V. V.
A1  - Janietz, Dietmar
T1  - Evolution of interdigitated molecular packing of discotic liquid crystals across interface
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Janietz, Dietmar
T1  - Structure formation of new triazine modified amphotropic discotics : light on organized molecular systems
Y1  - 1995
ER  - 
TY  - BOOK
A1  - Janietz, Dietmar
T1  - Flüssigkristalle in dünnen organischen Schichten
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Janietz, Dietmar
A1  - Festag, R.
A1  - Schmidt, C.
A1  - Wendorff, Joachim Heinz
T1  - Amphotropic oligomeric 1,3,5-triazines containing disc-shaped pentaalkyne and triphenylene side groups
Y1  - 1996
ER  - 
TY  - JOUR
A1  - Goldmann, Daniela
A1  - Janietz, Dietmar
A1  - Schmidt, C.
A1  - Wendorff, Joachim Heinz
T1  - Disc-shaped mesogens based on 1,3,5-triazines : variation and induction of columnar mesophases through complementary intermolecular interactions
Y1  - 1996
ER  - 
TY  - THES
A1  - Janietz, Dietmar
T1  - Organisation und Funktion : mesomorphe Aggregationsformen und Grenzflächenverhalten multifunktioneller discotischer Flüssigkristalle
Y1  - 1996
ER  - 
TY  - JOUR
A1  - Janietz, Dietmar
T1  - Covalently linked donor-acceptor mesogens based on disc-shaped penta-alkynes
Y1  - 1996
ER  - 
TY  - JOUR
A1  - Janietz, Dietmar
A1  - Katholy, Stefan
A1  - Dietzel, Birgit
A1  - Brehmer, Ludwig
T1  - Monolayer behaviour of two-fold hydroxy terminated sheet-like Tetrakis(phenylethynyl) benzene derivatives
Y1  - 1997
ER  - 
TY  - JOUR
A1  - Schröter, J. A.
A1  - Plehner, R.
A1  - Tschierske, C.
A1  - Katholy, Stefan
A1  - Janietz, Dietmar
A1  - Peñacorada, Florencio
A1  - Brehmer, Ludwig
T1  - Monolayer properties of a new family of amphiphiles with an unusual head-group topology
Y1  - 1997
ER  - 
TY  - JOUR
A1  - Marguet, S.
A1  - Markovitsi, D.
A1  - Goldmann, Daniela
A1  - Janietz, Dietmar
A1  - Praefcke, K.
A1  - Singer, D.
T1  - Spectroscopic properties of nematic discotic phenylethynylbenzene derivatives
Y1  - 1997
ER  - 
TY  - JOUR
A1  - Janietz, Dietmar
A1  - Ahuja, Rajeev C.
A1  - Möbius, Dietmar
T1  - Langmuir monolayers of sheet-shaped multialkyne amphiphiles
Y1  - 1997
ER  - 
TY  - JOUR
A1  - Goldmann, Daniela
A1  - Dietel, Reinhard
A1  - Janietz, Dietmar
A1  - Schmidt, C.
A1  - Wendorff, Joachim Heinz
T1  - Sheet-shaped mesogens based on 1,3,5-Triazines : variation of columnar mesophases through intermolecular hydrogen bonding
Y1  - 1998
ER  - 
TY  - JOUR
A1  - Janietz, Dietmar
T1  - Structure formation of functional sheet-shaped mesogens
Y1  - 1998
ER  - 
TY  - JOUR
A1  - Janietz, Dietmar
A1  - Katholy, Stefan
A1  - Brehmer, Ludwig
T1  - Monolayer properties of Amphiphilic Tetrakis(phenylethynyl)benzene compounds
Y1  - 1998
ER  - 
TY  - JOUR
A1  - Goldmann, Daniela
A1  - Janietz, Dietmar
A1  - Schmidt, C.
A1  - Wendorff, Joachim Heinz
T1  - Liquid crystalline 1,3,5-triazines incorporating rod-like azobenzene sub-units
Y1  - 1998
ER  - 
TY  - JOUR
A1  - Goldmann, Daniela
A1  - Mahlstedt, S.
A1  - Janietz, Dietmar
A1  - Busch, P.
A1  - Schmidt, C.
A1  - Stracke, A.
A1  - Wendorff, Joachim Heinz
T1  - Mesomorphic donor-acceptor twin molecules with covalently linked sheet-like pentaalkyne and nitrofluorenone subunits
Y1  - 1998
ER  - 
TY  - JOUR
A1  - Stracke, A.
A1  - Wendhorff, Joachim Heinz
A1  - Goldmann, Daniela
A1  - Janietz, Dietmar
A1  - Stiller, Burkhard
T1  - Gain effects in optical storage : thermal induction of a surface relief grating in a smectic liquid crystal
Y1  - 2000
ER  - 
TY  - JOUR
A1  - Goldmann, Daniela
A1  - Nordsieck, A.
A1  - Janietz, Dietmar
A1  - Frese, T.
A1  - Schmidt, C.
A1  - Wendorff, Joachim Heinz
T1  - Smectic and columnar liquid crystalline phases through charge-transfer interactions
N2  - New heterocyclic electron donors based on. a 1,3,5-triazine nucleus are presented. Three phenyl rings are grafted to the triazine core either via secondary amino groups or by a direct C,C-linkage and a specific number of decyloxy chains is attached to the molecular periphery. The compounds are non-liquid crystalline in their pure states. Lamellar or columnar mesophases are induced by attractive interactions with electron acceptors
Y1  - 2004
SN  - 1058-725X
ER  - 
TY  - JOUR
A1  - Goldmann, Daniela
A1  - Janietz, Dietmar
A1  - Schmidt, C.
A1  - Wendorff, Joachim Heinz
T1  - Columnar liquid crystalline phases through hydrogen bonding and nanoscale segregation
N2  - Two columnar phases forming 2,4,6-triarylamino-1,3,5-triazines have been investigated in binary mixtures with calamitic and non-liquid crystalline benzoic acids carrying one or two alkoxy chains at the aromatic core. The triazines form hydrogen bonded aggregates with the complementary acids. Each investigated equimolar mixture exhibits a columnar mesophase due to segregation of the H-bonded polar core region from the lipophilic aliphatic molecular segments. The cross sectional shape of cylindrical aggregates and, therefore, the two-dimensional lattice symmetries, hexagonal or rectangular, are defined by the number of alkoxy chains of the benzoic acid component
Y1  - 2004
SN  - 0959-9428
ER  - 
TY  - GEN
A1  - Inal, Sahika
A1  - Kölsch, Jonas D.
A1  - Chiappisi, Leonardo
A1  - Janietz, Dietmar
A1  - Gradzielski, Michael
A1  - Laschewsky, André
A1  - Neher, Dieter
T1  - Structure-related differences in the temperature-regulated fluorescence response of LCST type polymers
N2  - We demonstrate new fluorophore-labelled materials based on acrylamide and on oligo(ethylene glycol) (OEG) bearing thermoresponsive polymers for sensing purposes and investigate their thermally induced solubility transitions. It is found that the emission properties of the polarity-sensitive (solvatochromic) naphthalimide derivative attached to three different thermoresponsive polymers are highly specific to the exact chemical structure of the macromolecule. While the dye emits very weakly below the LCST when incorporated into poly(N-isopropylacrylamide) (pNIPAm) or into a polyacrylate backbone bearing only short OEG side chains, it is strongly emissive in polymethacrylates with longer OEG side chains. Heating of the aqueous solutions above their cloud point provokes an abrupt increase of the fluorescence intensity of the labelled pNIPAm, whereas the emission properties of the dye are rather unaffected as OEG-based polyacrylates and methacrylates undergo phase transition. Correlated with laser light scattering studies, these findings are ascribed to the different degrees of pre-aggregation of the chains at low temperatures and to the extent of dehydration that the phase transition evokes. It is concluded that although the temperature-triggered changes in the macroscopic absorption characteristics, related to large-scale alterations of the polymer chain conformation and aggregation, are well detectable and similar for these LCST-type polymers, the micro-environment provided to the dye within each polymer network differs substantially. Considering sensing applications, this finding is of great importance since the temperature-regulated fluorescence response of the polymer depends more on the macromolecular architecture than the type of reporter fluorophore.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 251 
KW  - anionic polymerizations
KW  - dilute aqueous-solutions
KW  - ether methacrylates
KW  - n-isopropylacrylamide
KW  - oligo(ethylene glycol) methacrylate
KW  - phase-transitions
KW  - protein interactions
KW  - solvatochromic fluorophore
KW  - thermoresponsive polymers
KW  - to-coil transition
Y1  - 2013
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-95379
SP  - 6603
EP  - 6612
ER  -